This invention relates to welding, joining or deforming thermoplastic workpieces by laser energy and, more specifically, refers to the construction of a laser diode array for providing uniform and intense laser radiation to a workpiece area for causing fast and uniform heating of the thermoplastic material at such area.
Welding and joining thermoplastic workpieces by laser energy is well known. The area at which workpieces are to be joined is illuminated with a laser beam and the resulting dissipation of energy, if of sufficient magnitude, causes a softening and flowing of thermoplastic material as pressure is applied to the softened material. Upon the cessation of the application of laser energy, the thermoplastic material cools and rigidifies, thus providing a joint.
The laser energy is provided, most suitably, by a laser diode energized from an electrical power supply operating in the continuous-wave mode. For providing a beam larger than that avaiable from a single diode, diode arrays have been developed. A typical commercial product comprises 19 diodes producing 20 W output power. An array of this type is relatively expensive and is limited also to illuminating a substantially straight, oblong shaped, workpiece surface.